Films that can be applied in fluid form for a structural seal based on polyurethanes or acrylate dispersions are known.
Compositions for liquid membranes based on polyurethane contain organic solvents and isocyanates and thus are not suitable for certain applications for ecological and toxicological reasons.
In addition, polyurethane-based liquid membranes can require an extensive substrate preparation to achieve sufficient adhesion. In this case, primarily adhesion promoter compositions, so-called primers, are used. For various reasons, it may be desirable or of considerable advantage to dispense with adhesion-promoting compositions in the application of a liquid membrane. Thus, for example, in addition to a cost advantage, the primer-less application of film also entails a time advantage, since the application and the aeration of the adhesion-promoting composition can be dispensed with. In addition, the primerless application of the film also has ecological advantages, since primers very often contain large amounts of volatile, organic solvents, so-called VOCs (Volatile Organic Compounds).
Polyurethane compositions can often have relatively short shelf lives and that they have to be modified for the application on vertical surfaces to prevent the composition from running off.
In contrast, compositions for liquid membranes based on acrylate dispersions are free of organic solvents and have a relatively long shelf life of up to 12 months. They are considerably less UV- and weather-resistant and can be applied on a limited number of substrates because of deficient adhesion.
In addition, known liquid membranes have disadvantages relative to their flammability properties, which can be problematic in the sealing of occupied buildings from the standpoint of safety.